Aspects of the present disclosure relate to apparatuses, devices, and methods involving capacitive isolation.
Aspects of the present disclosure relate to the transmission of data between circuits that operate in different voltage domains. For example, circuits may be galvanically isolated using capacitive coupling on signal paths between the circuits. As a result of such isolation, the circuits operate in separate voltage domains that are not referenced to one another by a common ground voltage level. As such, large voltage differences may arise between the corresponding voltage domains. Galvanic isolation has been used for a variety of different applications. For instance, galvanic isolation can be provided between multiple integrated circuit chips, which can be located within the same package or in different packages. Signals can be passed between the integrated circuits using galvanic isolation techniques.
One method of galvanic isolation uses capacitors on signal paths between two circuits as a means of blocking DC voltages and attenuating low-frequency signals while transmitting high-frequency signals. Due to large voltage differences that may arise between isolated voltage domains for some applications, capacitors having high breakdown voltage may be required. However, physical space constraints may make it difficult to implement capacitors having the required breakdown voltage. For example, a parallel plate capacitor may be implemented alongside other circuitry in an integrated circuit (IC) using conventional processes (e.g., CMOS, complementary metal-oxide-semiconductor). Two capacitive plates are implemented in different metallization layers of the IC and are separated by a dielectric layer. The breakdown voltage of the parallel plate capacitor is dependent on the thickness of the dielectric layer. For higher voltage applications, the thickness of the dielectric layer is increased to provide a higher breakdown voltage. However, in certain CMOS processes, the maximum dielectric thickness that can be implemented is limited to about 5-10 um. For some applications, this thickness is not sufficient to guarantee sufficient breakdown voltage.
Aspects of the present disclosure relate to the transmission of data between circuits that are isolated from one another. For example, circuits may be galvanically isolated using capacitive coupling on signal paths between the circuits. As a result of such isolation, the circuits operate in separate voltage domains that are not referenced to one another by a common ground voltage level. As such, voltage differences may arise between the corresponding voltage domains. In certain instances, the voltage differences can be relatively large in comparison to the voltages within each of the separate voltage domains.